Rocket fin



ROCKET FIN Filed Feb. '7, 1946 JNVENTOR. 12 12- JOHN IN. BUSACKER 34 BY /g, 6%

ATTORNEY Patented May 20,

Eo PATIENT :"L BQ O CKET FIN. r Jonm-w. Busackei'," Houston, Tex assignoi' to the United States of America as-representd by the Secretary of the Navy Application February 7, 19 ie,.s'er'i 1Nj6 .-'s4s;i6

2 Claims. 1

This invention relates to a fin structure for projectiles, and more particularly to a fin structure adapted to be released automatically from a projectile.

In the operation of rocket propelled and other missiles at very high velocities, it is essential to keep the size of control surfaces and/or stabilizing fins as small as possible to keep drag at a minimum. While small control surfaces or fins work well at high speed, they are not large enough to function properly when the speed is low, as during acceleration. It is therefore necessary to provide larger surfaces during the time the projectile is traveling at relatively low velocities.

Accordingly, one object of this invention is to provide auxiliary fins on a projectile with provisions for release of the fins when the projectile approaches its operating speed.

Another object of the invention is to provide a releasable projectile fin assembly which is simple in structure and positive in operation.

These and other objects of the invention will be obvious from the following specification and the accompanying drawing, in which Fig. 1 is a perspective view of a portion of a high velocity rocket type projectile before launching, showing the auxiliary fins in place;

Fig. 2 is an exploded perspective view of the auxiliary fin structure; and

Fig. 3 is a cross-sectional view taken in the plane 33 of Fig. 1. I

In the preferred embodiment of the invention shown in the drawing, a rocket type projectile In is provided with fixed stabilizing fins I l spaced in quadrature about the rear end of the projectile and an auxiliary fin structure consisting of a foundation band constituted by two semi-cylindrical metal band sections I2 and |2a. Two rectangular finsl l extend radially from each band and are disposed at angles of substantially 90 degrees with respect to each other. These fins comprise strips of sheet metal folded over and spot welded, leaving free ends bent outwardly in opposite directions to form mounting flanges Ma which are spot welded to the band sections l2 and 12a.

The band sections are held together by an external lug IS on one end portion of the band [2 which cooperates with a similar lug [B on the band 1211, the lugs being normally secured in cooperative relationship by screws 20. The other ends of the band sections are provided with apertured lugs 22, 22a and 26 having alignable bores and cooperating so as to receive a locking pin 28 which fits tightly within said lugs 22, 22a and 26.

2 If desired the bore and pin 28 may be slightly tapered to insure a tight fit. The end 30' of the pin is chamfered to eliminate the possibility of its being upset in operation and thereby becoming jammed in the bore. A portion 32 of the bore within lug 22 is of enlarged diameter to accommodate an electrically operable delayed action squib 34 which is held in place by a setscrew 36. The electrical leads 34a from the squib 34 are connected to the wires 38 which connect the squib (not shown) of the rocket motor to a plug 39 for connecting the squib to a conventional firing circuit (not shown) for firing the rocket motor (not shown). A rocket having a motor ignitible by an electrical squib is described in the copending patent application of Charles C. Lauritsen, Ser. No. 481,645, filed April 2, 1943, now Pat. No. 2,469,350.

To assemble the auxiliary fin structure, the bands I2 and l2a are fitted around the missile l0 behind the permanent fins I l, the pin 28 is driven into place to hold the connecting lugs 22, 22a and. 26 together, the band sections are tightened by means of the screws 20 in the lugs l6 and I8; and a delay-action squib 34 is inserted in the bore 32 where it is secured by the set-screw 36. The electrical leads of the squib are connected to those of the rocket-propellent squib (not shown) so that action of the squib 34 is initiated when the propellant is fired. The delay time of the squib 34 is such that the rocket propellant brings the missile approximately to its ultimate speed before squib 34 explodes. The explosion of squib 34 drives pin 28 out of the bore in the lugs 22, 22a and 26, releasing the grip of the band sectors [2 and 12a on the body In of the missile. The drag of the air on the fins I4 and other parts of the auxiliary fin assembly then causes said assembly to slide off the rear end of the missile which continues its fiight at high velocity adequately stabilized by the smaller permanent fins ll.

While there is herein described a preferred embodiment of the invention, it is to be understood that the field of the patent is not to be limited thereto, but is intended to cover also all modifications of the invention falling within the scope of the appended claims.

What is claimed is:

l. A releasable fin structure for a projectile, comprising two semi-cylindrical foundation elements surrounding said projectile, radial fins carried by said elements, threaded means fastening said foundation elements together along one pair of adjacent edges, the other pair of adjacent edges having interenga lng portions, a member passing through said interengagi s' portions to maintain said portions engaged, and a delay action squib carried by the projectile and located adjacent said member, whereby detonation of the squib will force the said member out of the interengagin portions to an extent suflicient to release the fin structure.

2. A releasable fin structure for a projectile, comprising two foundation elements together forming a band surrounding said projectile, radial fins carried by said elements, adjustable means fastening said foundation elements together along one pair of adjacent edges, the

other pair of adjacent edges being formed as matl5 ing apertured lugs, a pin passing through the apertures in said lugs to maintain said foundation elements engaged, and a delay action squib carried by the projectile and located adjacent said pin, whereby detonation of the squib will force said pin out of the lugs to an extent sufiicient to release the fin structure.

JOHN W. BUSACKER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,318,926 Settle Oct. 14, 1919 1,923,612 Bull Aug. 22, 1933 2,434,162 Imber Jan. 6, 1948 V FOREIGN PATENTS Number Country Date 380,734 Italy May 31, 1940 

